As disclosed, for example, in Patent Literature 1, the configuration of a conventional high-frequency package is composed of a first dielectric substrate having signal lines and grounding conductors on its surface layer on the back side, a high-frequency element mounted on the surface layer on the back side of the first dielectric substrate, a second dielectric substrate having signal lines and grounding conductors on its surface layer on the front side, and connection conductors, wherein the high-frequency element is mounted on the surface layer on the back side of the first dielectric substrate, the high-frequency element is configured such that it is in between the surface layer on the back side of the first dielectric substrate and the surface layer on the front side of the second dielectric substrate, and the connection conductors connect the grounding conductors of the first and second dielectric substrates so as to surround the high-frequency element, thereby having a shielded space.